Ecosystems under pressure put pressure on scientists

From individuals to species to the entire food web – climate change is noticeable at all levels of the Arctic marine ecosystem. But no one knows how much the system can tolerate. What we know for certain is that everything is interconnected and significantly more research is needed.

In September 2014, tens of thousands of walruses were observed on a beach near Point Lay in Alaska.Photo: (Corey Arrardo / NOAA/NMFS/AFSC/NMML). Front photo: Observer monitors nesting black-legged kittiwakes on Spitsbergen. Photo: Øystein Varpe, University Centre of Svalbard.

By Malin Avenius // Science journalist

In September 2014, tens of thousands of walruses were observed on a beach near Point Lay in Alaska, and aerial photographs showing the animals jam-packed together were published in newspapers all over the world. Research scientists believe it is the lack of sea ice that has made females and young haul out to rest on land a couple weeks’ swim away from the mussel banks where they find their most important food supply.

“The changes we are observing in the Arctic ecosystem have to do with a number of stressors that have major impact on biological and biogeochemical processes, the interaction between animal predators and their prey, and the entire dynamics of the ecosystem,” said Jacqueline Grebmeier, research professor at the University of Maryland’s Center for Environmental Science and keynote speaker at the first FRAM Science Days.

“It’s about there being less sea ice, warmer water, changes in food supply, marine pollution and migration northwards,” she continued.

New bottom-living species

In the western Arctic, grey whales are migrating ever further north in the hunt for food, and the endangered spectacled eider duck, a specialised diver that uses sea ice as a platform, is having ever greater difficulties finding food. The results Jacqueline Grebmeier presented included new bottom-living species establishing themselves around the Bering Strait; this is changing the conditions that sustain birds and marine mammals. But the connection between these things is both complicated and largely unknown, and researchers need considerably more data that cover both long periods of time and large geographical areas in the Arctic. She also pointed out that we need better knowledge of seasonal variations and we need to work in a more interdisciplinary manner – summarising in advance several of the recurring themes of the two-day conference.

Gathered at the ice’s edge

If the spectacled eider in the western Arctic uses sea ice when it searches for food, the black-legged kittiwake benefits from the ice in Svalbard’s glaciers. Together with the ivory gull, fulmar, glaucous gull and black guillemot, the black-legged kittiwake is enticed by the rich food supply to be found where glaciers meet the sea, said Hallvard Strøm from the Norwegian Polar Institute.

“The phenomenon of a large number of seabirds gathering at a glacier’s edge is well-known, but not well-documented. We don’t know quite what they eat there, but the stomachs of seabirds caught close to glaciers contain krill, naked sea butterfly and arctic cod.”

Ringed seals and beluga whales also gather at the seaward edge of the glaciers around Svalbard, which make up a total of 860 kilometres. As yet. The researchers don’t know what the ongoing melting of these glaciers will mean for birds and mammals in the future.

Ice melting away in Greenland

In Greenland, Helen Johnson, from the Universities of Oxford, UK and Bergen, Norway, is also studying the area where glaciers meet the sea, but from a completely different perspective. She is a physical oceanographer and is studying what happens hydrographically in fjords where glaciers flow into the sea. In recent decades, the melting of Greenland’s inland ice has quadrupled, and contributed one quarter of the global rise in sea level. But the melting affects the marine environment in several other ways as well.

“The freshwater from melting glaciers is becoming a significant factor in the polar oceans, and may affect the deep water circulation and the climate. Locally, it creates stress in the ecosystem by altering the stratification between water masses and by bringing more nutrients into the sea. This can change the primary production and the structure of the food web,” she explained.

Thinner ice

Another change in the Arctic environment that was discussed at the FRAM Science Days 2015 was the increase in the amount of solar radiation that reaches the seawater. This has to do with less and thinner ice and – above all – with there being less snow to reflect the light waves. Eight times more radiation is now penetrating to the marine ecosystem, said Mats Granskog of the Norwegian Polar Institute. How this will affect microalgae, the very basis of the food web, remains to be seen – and is intertwined with the effects of other stressors.

“The consequences of increased solar radiation cannot be studied in isolation. Factors like warming, larger amounts of freshwater, ocean acidification and more light together affect the biogeochemical processes, often in unpredictable ways.”

A nightmare

“Multiple stressors are a nightmare.” This was how Howard Browman of the Institute of Marine Research described the same problem, and he believes that everyone who works with laboratory experiments is well aware of it. His presentation described recent efforts to learn more about ocean acidification, which is caused by the ocean absorbing much of the carbon dioxide we emit into the atmosphere. He exhorted his colleagues to adopt an organised scepticism to the multitude of reports showing how a lower pH value affects different organisms, since many authors have forgotten to factor in natural selection over the course of several generations, forgotten how much animals can adapt and how much the acidity can vary in their natural habitats.

“Instead of focusing solely on the individuals that died in an experiment, we should look at those who survived. If one group actually coped well, that can be important in the longer term.”

Changes in the ecosystem

Rather than studying the sensitivity of individuals and individual species, Raul Primicerio at the University of Tromsø has devoted himself to studying the entire ecosystem. As keynote speaker on the second day of the conference, he introduced the session entitled Ecosystem Changes. His primary focus is not the direct effects of environmental change on animal life (such as the fact that cod and haddock have migrated further north), but the impact of such changes on the sensitivity of the entire ecosystem – which will determine, for example, how much pressure from fisheries the Barents Sea will be able to cope with in the future.

“When it comes to individuals, we have the tools to study how sensitive they are, but as yet we don’t have those tools for the entire ecosystem. If we want to achieve ecosystem-based management, that’s something we have to work on,” he told the audience.

We need ecosystem prognoses

Lis Jørgensen, of the Institute of Marine Research, also called for the tools to enable wise future management of the ecosystem, and said we must become better at identifying human activity that impacts negatively on the system.

“We need to be able to make ecosystem prognoses, roughly the same way as we predict the weather!”

Along the Norwegian coast from Trondheim and northward, an ongoing change no one had predicted shows that not all transformation of the ecosystem is necessarily a bad thing. In places where sea urchins had taken over and transformed billowing kelp forests into desert-like ocean floors, the long brown algae are now returning. And with them, an ecosystem is being re-established – an ecosystem that is very important for biological diversity along the coast, said Hartwig Christie of the Norwegian Institute for Water Research (NIVA).

“We don’t know why the sea urchin population was so successful 45 years ago, but we are now carefully monitoring its decline. It is a cold-water species and is under stress, mainly because the water is becoming warmer, but it is also being eaten by invasive snow crabs and king crabs. Their role is something we need to study in greater detail.”

The first FRAM Science Days attracted more than 100 delegates. Photo: Helge M. Markusson, Fram Centre

Remote analysis provides knowledge

Even if many of the speakers at the FRAM Science Days observed that we still lack a great deal of knowledge about the marine ecosystem in the Arctic, Rolf Gradinger of the University of Alaska Fairbanks and the Institute of Marine Research pointed out that there is also a great deal we do know.

“Thanks to remote analysis, we have detailed and comprehensive knowledge of the sea ice, its distribution, concentration, seasonal variations and drift.”

Gradinger also hopes that DNA technology will come to good use in future mapping of organisms in the sea.

At the concluding panel debate there was widespread agreement that interdisciplinary cooperation is vital for progress, likewise that the Arctic ecosystem offers a major future challenge for researchers. The end of Rolf Gradinger’s presentation captured perfectly the conference delegates’ enthusiasm for the task: “It will be great fun and very exciting to be a part of it all.”

Fram Forum is published once a year on behalf of FRAM - High North Research Centre for Climate and the Environment. Its aim is to imform the general public about the wide activities that take place within the Fram Centre. The magazine is available online free of charge to any and all who are interested in topics related to climate, environment and people in the high north. Do you want a printed copy, please send an email to post@framsenteret.no